Abstract
In contrast to bony metastases, soft tissue metastases from carcinoma are rare. We reviewed all referrals to our Sarcoma Unit over an eight-year period, and found an incidence of soft tissue metastases from carcinoma of 1.4%. The most common mode of presentation was a painless soft tissue lump in a patient with an occult primary. Lung and kidney were the most frequent primary sources. Overall, prognosis was poor, with a mean survival of 9.4 months. Renal tumours however had a much better prognosis that other types of tumours. Treatment should be individualised according to the underlying disease and the prognosis. Although much rarer than primary soft tissue sarcomas, soft tissue metastases from carcinoma should remain a differential diagnosis in any patient presenting with a suspicious soft tissue lump.
Introduction: Carcinoma most commonly metastasises via the lymphatic system firstly to the regional lymph nodes and then into the general circulation. Dependent upon the primary site of tumour, metastases from carcinoma commonly occur to the lungs, liver and bone. Distant metastases to the soft tissues are rare. There are few published case series (1,2) – the majority of the literature containing only case reports. We report a series of 10 cases of soft tissue metastases from carcinoma, collected from retrospective review of the case notes of consecutive patients referred over a eight year period to our Sarcoma Unit with a soft tissue lump, suspicious of a sarcoma.
Patients and Methods: We retrospectively reviewed the case notes of consecutive patients over a eight year period (April 1995 – April 2003) referred to our Unit with a soft tissue lump, suspicious of a sarcoma. All patients underwent magnetic resonance (MR) scanning, and then trucut or open biopsy of the lesion. Dependent on the histological and MR findings, patients then underwent computer tomography (CT) of the chest and ultrasound examination of the abdomen. Included in this series were all patients with a histologically proven, soft tissue (skeletal muscle or subcutaneous tissue) metastatic carcinomatous deposit.
Demographic, diagnostic, clinical, radiological and treatment data was collected on all patients.
Results: Of the 702 referrals to our Unit over the eight-year period with a soft tissue lump suspicious of a sarcoma, 10 cases proved to be soft tissue metastases from carcinomas (incidence 1.4%). Data for the 10 patients comprising the series is shown in Table 1. Eight of the patients were male, two were female. The mean age at presentation was 68 years (range 39–85 years). Two patients presented with a painful lump, and in the other eight patients the lump was asymptomatic. The involved sites included the thigh in four cases, the arm in three cases, the back, buttock and axilla one each.In nine cases, the soft tissue lump was the presenting symptom of an occult primary carcinoma, whilst in one case (Case 4); the patient had a history of previous excision of a hypernephroma. The sources of primary carcinoma were small cell carcinoma of the lung in 4 cases, renal clear cell carcinoma in 3 cases, large bowel adenocarcinoma in 1 case, prostate 1 case, and in 1 case the primary site was unknown.
All but one patient (Case 6) underwent radiotherapy or chemotherapy or both. Case 6 presented with a soft tissue lump over the shoulder, which on biopsy was found to be metastatic adenocarcinoma of large bowel origin. CT scan of the head confirmed multiple brain metastases. He declined any treatment and died within 2 months of presentation. In total, nine of the ten patients have died of their disease. The mean duration from diagnosis of soft tissue metastasis to death was 9.4 months (range 2–31 months). The duration of survival was significantly better for metastatic carcinoma of the kidney (23 months) compared to the other carcinomas (7 months).
Discussion: The most commonly reported primary carcinomas to result in soft tissue metastases are those of the lung, kidney and colon (1–3), contrasting with those carcinomas which commonly metastasise to bone such as prostate, breast and thyroid which only very rarely metastasise to the soft tissues. Damron and Heiner (1) who reported the largest series to date however had no cases where the patients primary site of carcinoma was of renal or colon origin and suggested that these cases were over-represented in the literature. Our series differs from their findings, concurring instead with the other published literature. Histologically, the most common diagnosis is adenocarcinoma, though many have been reported (1–3).
Soft tissue metastases from carcinoma are rare, which again contrasts to bony metastases from carcinoma. Tolia and Whitmore (4) reviewed 586 patients with renal cell carcinoma, and whilst a quarter had evidence of distant metastases at presentation, no patient had soft tissue metastases. Chandler et al (5) reported on 726 patients who died following metastatic renal carcinoma; only 3 patients had soft tissue metastases, all of which were only found at autopsy. Our series, which reviewed all patients referred to our Unit over a eight year period with a soft tissue lump initially suspicious of a sarcoma, found an overall incidence of 1.4%.
Damron and Heiner (1) reported that the most common mode of presentation was a painful soft tissue lump. In our series however, the majority were painless. Whilst for most, the lump is the first sign of an occult malignancy, renal cell carcinomas tend to be different, often presenting as a solitary soft tissue deposit a few months to up to 16 years after the initial diagnosis of renal cell carcinoma has been made (1,2). Our series agreed with these findings; only in 1 case (Case 4) was there evidence of previously documented carcinoma prior to presentation with the soft tissue lump.
All patients in our series underwent pre-operative MR scans, the appearances of which were not diagnostic of metastases, though highly suggestive of malignancy. Subsequently patients underwent either Tru-cut or open biopsy which gave the definitive diagnosis. As part of the pre-operative work-up, all patients had a CT of the chest and abdominal ultrasound scanning.
Rao et al (6) reported 5 cases of soft tissue metastases from primary sarcoma, concluding that metastases in these cases were seen as late events and survival was generally poor. In our series of soft tissue metastases from carcinoma, we also found that prognosis was poor (averaging 9.4 months), especially when the primary carcinoma was lung, though the prognosis, if the primary was renal carcinoma was less bleak.
Conclusions: Although rare, soft tissue metastases from carcinoma should remain a differential diagnosis in any patient presenting with a suspicious soft tissue lump. Whilst the MR scan appearances were suggestive of malignancy, they were not diagnostic of metastases. Tru-cut or open biopsy was reliable in confirming the diagnosis of carcinoma and helpful in the detection of the possible origin of the primary. The most common primary sites were lung, kidney and bowel.
The abstracts were prepared by Mr Roger Tillman. Correspondence should be addressed to BOOS at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PN
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